Wheel suspension and retraction apparatus

ABSTRACT

A wheel suspension and retraction apparatus ( 2 ) for an amphibious vehicle comprises a suspension unit having transverse upper and lower suspension links ( 4, 8 ); spring and damper unit ( 12 ), and suspension upright ( 6 ) supporting wheel ( 10 ), and pivotally connected to outboard ends of links ( 4  and  8 ). The wheel retraction mechanism has a retraction linkage ( 14, 16, 18 ), pivotably connectable to the vehicle, and an actuator ( 38 ) for moving the wheel suspension between a protracted position for land use and a retracted position for use on water. The retraction mechanism supports the suspension unit spaced apart transversely from the vehicle. Tie bar ( 16 ) is connected to upper retraction arm ( 14 ) at an intermediate location ( 30 ) to ensure a large angle of tilt on retraction, to ensure that the wheel is retracted above hull line ( 156 ). The wheel suspension does not have to be compressed on retraction.

RELATED APPLICATIONS

This application is a U.S. national phase of PCT/GB2008/000127, filedJan. 15, 2008, which claims priority from Great Britain ApplicationSerial No. 0700766.9, filed Jan. 15, 2007.

The present invention relates' to a wheel suspension and retractionapparatus for an amphibious vehicle, and to an amphibious vehicle havingsuch a wheel suspension and retraction apparatus. In particular, itrelates to apparatus which functions as suspension for a wheel when thevehicle is on land and which allows retraction of the wheel above awaterline of an amphibious vehicle.

Many amphibious vehicles have been designed with wheel retractionmechanisms, to lift the wheels when the vehicle is on water. Many of thewheel retraction systems are complicated and/or provide poor suspensionwhen the vehicle is used on land.

U.S. Pat. No. 5,755,173 describes use for each wheel of atransversely-extending single arm which swings upwardly around alongitudinal axis of the vehicle. This results in compromised suspensionon land, as there is too much camber change on bump and on rebound.

WO02/16152 describes a trailing arm suspension. This gives zero camberchange to the wheel when one side of the car loads up during cornering.This provides for poor road holding when on land. U.S. Pat. No.3,755,838 also describes a trailing arm suspension. This again providespoor road holding on land.

The present invention provides, in a first aspect, a wheel suspensionand retraction apparatus for an amphibious vehicle comprising asuspension unit having a transversely extending upper suspension link, atransversely extending lower suspension link and a suspension uprightfor supporting a wheel, said suspension upright pivotally connected to,in use, outboard ends of the upper and lower suspension links. A wheelretraction mechanism having a retraction linkage pivotally connectableto the vehicle and an actuator for pivoting the retraction linkagebetween, in use, a protracted position and a retracted position. Theretraction mechanism supports, in use, the suspension unit spaced aparttransversely from the vehicle with the suspension unit supported on thevehicle only via the retraction mechanism. When the retraction linkageis protracted then the retraction linkage holds the suspension unit in adeployed wheel position for operation of the vehicle on land, and onretraction, in use, the retraction mechanism lifts the suspension unitupwardly to a retracted wheel position, for use of the vehicle on water.

The present invention provides, in a second aspect, a wheel suspensionand retraction apparatus for an amphibious vehicle comprising asuspension unit having a transversely extending upper suspension link, atransversely extending lower suspension link and a suspension uprightfor supporting a wheel, said suspension upright pivotally connected tooutboard ends of the upper and lower suspension links. A wheelretraction mechanism having a retraction linkage pivotally connectableto the vehicle and an actuator for pivoting the retraction linkagebetween, in use, a protracted position and a retracted position. Theretraction linkage comprises a lower retraction link pivotally connectedat, in use, an outboard end thereof to the lower suspension link andpivotally connectable at an inboard end thereof to the vehicle. When thelower retraction link is protracted the retraction linkage holds thesuspension unit in a deployed wheel position for operation of thevehicle on land, and on retraction, the retraction mechanism lifts thesuspension unit upwardly to a retracted wheel position, for use of thevehicle on water.

Thus, the wheels can be retracted using a relatively simple mechanism.While on land the suspension provides good road holding ability.Standard parts may be used for several of the key components, reducingdesign and manufacturing costs.

Embodiments of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic side elevation of the wheel retraction apparatusof the present invention, in a fully extended state;

FIG. 2 is a schematic side elevation of the wheel retraction apparatusof the present invention showing limited bump travel;

FIG. 3 is a schematic side elevation of the wheel retraction apparatusof the present invention showing full bump travel;

FIG. 4 is a schematic side elevation of the wheel retraction apparatusof the present invention in a partially retracted state;

FIG. 5 is a schematic side elevation view of the wheel retractionapparatus in a fully retracted state;

FIG. 6 is a perspective view of a second embodiment of the presentinvention in which the wheel retraction apparatus is in a fully extendedstate;

FIG. 7 is a side elevation view of the extended wheel retractionapparatus of FIG. 6;

FIG. 8 is a side elevation view of the wheel retraction apparatus ofFIG. 6 in a fully retracted state.

FIG. 1 shows a wheel retraction apparatus 2 fitted with a wheel 10, foruse on an amphibious vehicle. The amphibious vehicle (not shown) is abuoyant vessel, having wheels including wheel 10. The amphibious vehicleincludes a motor, for example a petrol or diesel internal combustionengine. One or more of the wheels 10 will be driven by the motor onland. The motor may also provide power to a marine propulsion unit, forpropelling the vehicle on water. The wheel retraction apparatus 2according to the present invention can be used for steerable wheels ornon-steerable wheels, and for driven wheels or non-driven wheels, butfor the sake of simplicity is shown for a non-steered non-driven wheel10.

The amphibious vehicle can operate on land in a land mode, and switch toa water mode in which it can be used on water. The amphibious vehicle isable to plane on the water in the water mode.

FIG. 1 shows the wheel 10 rotatably connected to a suspension upright 6(sometimes called a knuckle or a hub carrier). The suspension upright 6has a top end rotatably connected to an upper suspension link 4 by apivot 22. A bottom end of the suspension upright 6 is rotatablyconnected to a lower suspension link 8 by a pivot 24. The uppersuspension link 4 and the lower suspension link 8 extend transversely ofthe vehicle, inwardly from the suspension upright 6, i.e. closer to acentre line of the vehicle.

The upper suspension link 4 and lower suspension link 8 are preferablyeach wishbone-shaped arms with the apex of each arm connected to thesuspension upright 6. The upper suspension link 4 is shorter than thelower suspension link 8.

In the figure there can be seen a spring-and-damper unit 12 which ispreferably a conventional spring-over-damper unit as illustrated. Thespring-and-damper unit 12 is pivotally connected at its top end to aninboard end of the upper suspension link. The spring-and-damper unit 12is connected at its bottom end to lower suspension link 8, nearer to theoutboard pivot 24 than to an inboard pivot 28 of the lower suspensionlink.

The upper and lower suspension links 4, 8, the suspension upright 6 andthe spring-and-damper unit 12 together form a double wishbone suspensionunit. Double wishbone suspension units are well known in use inroad-going vehicles and provide good levels of road holding ability. Theuse of a conventional geometry double wishbone suspension allows off theshelf components to be readily used, reducing design and manufacturingcosts for the amphibious vehicle. The ride handling characteristics ofthis layout are well known, and so can be adapted or tuned to thespecific requirements of the vehicle, in order to provide a comfortableride and/or good cornering capabilities.

The double wishbone suspension unit is not directly connected to thevehicle body. The suspension unit is secured to the vehicle and spacedapart from the vehicle by a retraction mechanism. The retractionmechanism has a retraction linkage which can rigidly support thesuspension unit in a protracted position to allow the suspension unit tofunction when the vehicle is on land. The retraction mechanism isfurther operable to retract the suspension unit when the vehicle is onwater.

The retraction mechanism will now be described with reference to FIG. 1.The retraction mechanism comprises upper retraction arms 14 (only oneshown in the figure, but these will be a pair of longitudinally-spacedapart arms), lower retraction arms 18 (only one shown in the figure, butthere will be a pair of longitudinally spaced-apart arms) and a tie baror bars 16. The bifurcated inboard ends of the upper suspension link 4are pivotally connected one each to the upper retraction arms 14 by apair of pivots 26 (only one shown). Inboard ends of the upper retractionarms 14 are pivotally connected to the vehicle body by a pair ofspaced-apart pivots 32.

The bifurcated ends of the lower suspension link 8 are pivotallyconnected one each to the lower retraction arms 18 by a pair of pivots28. Inboard ends of the lower retraction arms 18 are pivotally connectedto the vehicle body by a pair of pivots 34.

The tie bar or bars 16 has/have a lower end(s) pivotally connected tooutboard ends of the lower retraction arms 18 and lower suspension link8 at the pair of pivots 28. An upper end/upper ends of the tie bar(s) 16is/are pivotally connected to the upper retraction arms 14 at a pair ofpivots 30.

Pivots 22, 24, 26, 28, 30, 32, 34 all allow relative rotational movementof the attached members in the same plane or parallel planes. The pivots22, 24, 26, 28, 30, 32, 34 allow rotation about axes each substantiallyparallel to the longitudinal axis of the vehicle. This allows verticalmovement of the wheel 10 and also provides for tilting of the wheelabout an axis parallel to the longitudinal axis of the vehicle, as willbe described in more detail.

The upper retraction arms 14 and lower retraction arms 18 each comprisetwo arms. The separation of the arms may be uniform along their length,or the separation of the arms may reduce towards their outboard ends orin any other manner.

The upper retraction arms 14 and/or lower retraction arms 18 may each beformed as an “H” frame. This may reduce uneven loading of the arms, andincrease rigidity. This also improves the dimensional consistency of thesuspension.

An actuator 38 is provided in the retraction mechanism, in order toeffect protraction and retraction of the retraction mechanism duringmode change and also to hold the retraction mechanism stationary at allother times. The actuator 38 is in the form of a hydraulic ram. Thehydraulic ram 38 has an outboard end rotatably attached to the outboardend of a lower retraction arm 18 (or to both outboard ends of the lowerretraction arms 18) by the pivot 28. The outboard end of the ram 38 isrotatably attached to the vehicle body by a pivot 40. The wheel 10 istherefore secured to the vehicle at five points: two pivots 32, twopivots 34 and one pivot 40. The retraction mechanism is configured towithstand the forces experienced by the wheel 10.

Operation of the wheel retraction mechanism will now be described. Whenthe vehicle is in a land mode, the wheel retraction apparatus is in afully protracted state as shown in FIG. 1, in which the wheel 10 is incontact with a road or other ground. The hydraulic ram 38 is extendedand locked in position when the vehicle is in the land mode.

As the vehicle is driven, the double wishbone suspension unit willabsorb bumps in the road. FIG. 2 shows the retraction apparatus in partbump travel. The retraction mechanism remains locked in place, providingfixed inboard pivot points for the double wishbone suspension unit. Thewheel 10 has been urged upwardly by the bump in the road. Uppersuspension link 4 and lower suspension link 8 have rotated upwardlyabout pivots 26, 28 respectively. Upper suspension link 4 is shorterthan lower suspension link 8, so that the upward movement of the wheelresults in a small camber change of the wheel 10 towards an inboard sideof the vehicle, 6 as this aids road holding. The spring-and-damper unit12 is partially compressed during part bump travel, and resists theupward movement of the wheel 10 to keep the wheel 10 in contact with theroad.

During part bump travel the upper retraction arms 14, lower retractionarms 18 and tie bars 16 are locked stationary, and the function of thedouble wishbone suspension unit is not substantially affected by theability of the apparatus to retract.

FIG. 3 shows the wheel retraction apparatus in full bump travel. Thisshows the maximum intended rotation of the upper and lower suspensionlinks 4, 8. As for FIG. 2, the wheel retraction mechanism is locked toprovide stationary pivots 26, 28 for the double wishbone suspensionunit.

The retraction of the wheel 10, will now be described with reference toFIG. 4. The retraction is actuated by contraction of the hydraulic ram38. Since the hydraulic ram 38 is securely attached to the vehicle bypivot 40, the retraction urges pivots 28 generally towards pivot 40. Thepivots 28 are therefore lifted upwardly and inboard. Lower retractionarms 18 rotate upwardly about pivots 34. The tie bar(s) 16 moveupwardly, with its/their upper end(s) at pivot(s) 30 defining an arcaround pivot(s) 32. The movement of the tie bar(s) 16 causes the upperretraction arms 14 to rotate upwardly around pivots 32.

Due to the arrangement of the retraction links in the wheel retractionmechanism, the upper retraction arms 14 undergo a larger angle ofrotation than the lower retraction arms 18. In particular, this isbecause pivots 30 are relatively close to pivots 32. Thus, a first angleof rotation of pivot 28 about pivot 34, when the hydraulic ramcontracts, causes a larger second angle of rotation of the upperretraction arms 14 about pivots 32. The lower retraction arms 18 arelonger than the distance between pivots 30 and 32, and so the linearcontraction of the hydraulic ram 38 results in a smaller angle ofrotation of the lower retraction arms 18. The long length of the lowerretraction arms 18 also provides for long vertical travel of the doublewishbone suspension unit, allowing the wheel 10 to be retracted abovethe waterline of a deep V-hull amphibious vehicle.

The rotation of the upper retraction arms 14 and lower retraction arms18 carries the upper suspension link 4 and lower suspension link 8upwardly. Initially, the movement of the wheel 10 is substantially as ifit is rotated around pivot 34. The spring-and-damper unit 12 tends toexpand as the weight of the vehicle is taken off the wheel 10. Theexpansion of the spring-and-damper unit 12 is limited by a rebound stop(not shown) and reaches a maximum.

FIG. 5 shows the wheel retraction apparatus when the wheel 10 is fullyretracted. The wheel 10 is lifted a significant distance upwardly. Thewheel 10 has also been rotated in an inboard direction, anti-clockwiseabout pivot 28 as shown in FIG. 5. The wheel 10 has been rotated fromthe vertical by an angle larger than the rotation of the lowerretraction arms 18. The additional rotation of the wheel 10 is providedby the greater rotation of the upper retraction arms 14 than the lowerretraction arms 18.

When the wheel 10 is fully retracted, the wheel 10 is above a waterlineof the vehicle, even when a vehicle is cornering. The vehicle is able toplane on water without drag caused by the wheel 10.

The retraction mechanism is also operable to protract the suspensionunit from a retracted position into the state shown in FIG. 1. The wheelretraction apparatus has a good lifting capability in the event that thevehicle is beached, i.e. if the vehicle is run aground then the wheelscan be extended to contact a solid bed in shallow water and lift thevehicle upwards. Since the rotational axis of the wheels is close toparallel to the ground during the final stages of deployment the amountof tyre scrub in deployment is kept low.

FIGS. 6 to 8 show a second embodiment 102 of the wheel suspension andretraction apparatus. The most significant difference from the firstembodiment is the location and orientation of the hydraulic ram 138. Thehydraulic ram 138 is pivotally connected to a pivot 126 connecting anupper retraction arm 114 to bifurcated inboard ends of the uppersuspension link 104. In order for wheel 110 to be retracted, thehydraulic ram 138 contracts, urging pivot 126 in an inward and upwarddirection, and rotating it in an anti-clockwise direction as shown,about an inboard pivot 132. This movement causes the lower retractionarms 118 to rotate upwardly. As for the first embodiment, this resultsin the wheel 110 being lifted upwardly and tilting in an anti-clockwisedirection (as shown) to raise it clear of the water line of the vehicle.FIG. 8 shows a fully retracted position.

FIG. 8 also indicates a hull line of the vehicle as line 156. The hullhas a recess in which the wheel retraction apparatus is located. Aclosing panel 158 is movably locatable over the aperture once the wheelis retracted. The panel 158 can be attached to the lower retraction arm118. The hull, panel or closing mechanism may be as described in US2006/0189224 which is incorporated herein by reference.

FIGS. 6 to 8 show a driven wheel. A part of the drive train, for examplea differential 150, is shown. A drive shaft 152 connects thedifferential 150 to the wheel 110 via universal joints (not shown) in aknown manner.

The drive shaft 152 and closing panel 158 can also be used in the firstembodiment of the present invention. A steering arm may be connected tothe suspension upright to steer wheels 10. The steering arm will retractwith the suspension unit.

It should be noted that further refinements may be made to the apparatusdescribed above without departing from the essential inventive concept.For example, actuator 38 may be powered by electricity; magnetic drive;compressed gas; vacuum drive; a mechanical drive from a power take off;or by any other suitable means.

The suspension unit has been described as being supported on the vehicleonly via the retraction mechanism. This is intended to indicate that theretraction mechanism is substantially the only load bearing connectionsupporting the suspension unit. The suspension unit may have furtherconnections to the vehicle, for example steering tie rods, anti-rollbars, drive shafts or hydraulic hoses. Such devices are not consideredto bear a substantial part of the weight and loads of the suspensionunit.

The invention claimed is:
 1. A wheel suspension and retraction apparatusfor an amphibious vehicle comprising: a suspension unit having atransversely extending upper suspension link, a transversely extendinglower suspension link and a suspension upright for supporting a wheel,said suspension upright pivotally connected to, in use, outboard ends ofthe upper and lower suspension links; a wheel retraction mechanismhaving a retraction linkage pivotally connectable to the vehicle and anactuator for pivoting the retraction linkage between, in use, aprotracted position and a retracted position; wherein: the retractionmechanism supports, in use, the suspension unit spaced aparttransversely from the vehicle with the suspension unit supported on thevehicle only via the retraction mechanism; wherein when the retractionlinkage is protracted then the retraction linkage holds the suspensionunit in a deployed wheel position for operation of the vehicle on land;and on retraction, in use, the retraction mechanism lifts the suspensionunit upwardly to a retracted wheel position, for use of the vehicle onwater.
 2. The wheel suspension and retraction apparatus of claim 1,wherein in use the retraction linkage is pivotally attached to aninboard end of the upper suspension link and to an inboard end of thelower suspension link.
 3. The wheel suspension and retraction apparatusof claim 1 wherein in use the retraction mechanism is operable to rotatethe suspension unit upwardly and in an inboard direction.
 4. The wheelsuspension and retraction apparatus of claim 3 wherein the retractionmechanism is operable to tilt the suspension upright whilst lifting thesuspension unit.
 5. The wheel suspension and retraction apparatus asclaimed in claim 1 wherein the retraction linkage comprises: an upperretraction link pivotally connected at an outboard end thereof to theupper suspension link and pivotally connectable at an inboard endthereof to the vehicle, a lower retraction link pivotally connected atan outboard end thereof to the lower suspension link and pivotallyconnectable at an inboard end thereof to the vehicle; and a tie barpivotally connected between the upper retraction arm and the lowerretraction arm.
 6. The wheel suspension and retraction apparatus ofclaim 5 wherein the tie bar is pivotally connected to the upperretraction link at a point on the upper retraction link between inboardand outboard ends of the upper retraction link.
 7. The wheel suspensionand retraction mechanism of claim 5 wherein the tie bar is pivotallyconnected to the lower retraction link at the outboard end thereof. 8.The wheel suspension and retraction apparatus of claim 5 wherein thelower retraction link is longer than the upper retraction link.
 9. Thewheel suspension and retraction apparatus as claimed in claim 5 whereinthe actuator is a hydraulic ram pivotally connected at an outboard endthereof to the lower retraction link and pivotally connectable at aninboard end thereof to the vehicle.
 10. The wheel suspension andretraction apparatus of claim 5 wherein the actuator is a hydraulic rampivotally connected at an outboard end thereof to the upper retractionlink and pivotally connectable at an inboard end thereof to the vehicle.11. The wheel suspension and retraction apparatus of claim 1 wherein theupper suspension link is shorter than the lower suspension link.
 12. Thewheel suspension and retraction apparatus of claim 1 wherein the uppersuspension link and/or the lower suspension link are each in the form ofa wishbone.
 13. A wheel suspension and retraction apparatus for anamphibious vehicle comprising: a suspension unit having a transverselyextending upper suspension link, a transversely extending lowersuspension link and a suspension upright for supporting a wheel, saidsuspension upright pivotally connected to outboard ends of the upper andlower suspension links; a wheel retraction mechanism having a retractionlinkage pivotally connectable to the vehicle and an actuator forpivoting the retraction linkage between, in use, a protracted positionand a retracted position; wherein the retraction linkage comprises alower retraction link pivotally connected at, in use, an outboard endthereof to the lower suspension link and pivotally connectable at aninboard end thereof to the vehicle; wherein when the lower retractionlink is protracted the retraction linkage holds the suspension unit in adeployed wheel position for operation of the vehicle on land; and onretraction, the retraction mechanism lifts the suspension unit upwardlyto a retracted wheel position, for use of the vehicle on water.
 14. Awheel suspension and retraction apparatus as claimed in claim 13,wherein the retraction linkage is pivotally attached to an inboard endof the upper suspension link and to an inboard end of the lowersuspension link.
 15. The wheel suspension and retraction apparatus ofclaim 13 wherein the retraction mechanism is operable to rotate thesuspension unit upwardly and in an inboard direction.
 16. The wheelsuspension and retraction apparatus of claim 13 wherein the retractionmechanism is operable to tilt the suspension upright whilst lifting thesuspension unit.
 17. The wheel suspension and retraction apparatus asclaimed in claim 13 wherein the retraction linkage further comprises anupper retraction link pivotally connected at an outboard end thereof tothe upper suspension link and pivotally connectable at an inboard endthereof to the vehicle, and a tie bar pivotally connected between theupper retraction link and the lower retraction link.
 18. The wheelsuspension and retraction apparatus of claim 17 wherein the tie bar ispivotally connected to the upper retraction link at a point on the upperretraction link between inboard and outboard ends of the upperretraction link.
 19. The wheel suspension and retraction mechanism ofclaim 17 wherein the tie bar is pivotally connected to the lowerretraction link at the outboard end thereof.
 20. The wheel suspensionand retraction apparatus of claim 17 wherein the lower retraction linkis longer than the upper retraction link.
 21. The wheel suspension andretraction apparatus as claimed in claim 13 wherein the actuator is ahydraulic ram pivotally connected at an outboard end thereof to thelower retraction link and pivotally connectable at an inboard endthereof to the vehicle.
 22. The wheel suspension and retractionapparatus of claim 17 wherein the actuator is a hydraulic ram pivotallyconnected at an outboard end thereof to the upper retraction link andpivotally connectable at an inboard end thereof to the vehicle.
 23. Thewheel suspension and retraction apparatus of claim 13 wherein the uppersuspension link is shorter than the lower suspension link.
 24. The wheelsuspension and retraction apparatus of claim 13 wherein the uppersuspension link and/or the lower suspension link are each in the form ofa wishbone.
 25. The wheel suspension and retraction apparatus of claim17 wherein the lower retraction link and/or the upper retraction linkare formed as a pair of rigid members.
 26. The wheel suspension andretraction mechanism of claim 17 wherein the upper retraction linkand/or the lower retraction link is/are each configured as an “H” frame.27. An amphibious vehicle having the wheel suspension and retractionapparatus of claim 1.